Apparatus for drawing glass tubing



June 5, 1945. c. H. GREENE APPARATUS FOR DRAWING GLASS TUBING Filed May '7, 1941 Patented .lune 5, 1945 2,377,494 l APPARATUS FOR DRAWING GLASS TUBING Charles H. Greene,

Corning, N. Y., assignor to Corning Glass Works, Corning, N. Y., a. corporation of New York Application May 7, 1941, Serial No. 392,378

The present invention relates to apparatus for the continuous drawing of glass tubing, and is particularly concerned with the provision of a new and improved apparatus introducing a gaseous fluid into the tubing being drawn. e

The most extensively chines are those of the described in Danner used tube drawing mageneral form shown and patents, 1,219,709 and 1,220,201 and in' Vello patents, 2,009,326 and 2,009,793. For the purpose of describing the present invention it has been herein applied to the type of machine disclosed by the-Danner patents, although it is equally applicable to the Vello and other types of machines.

`-In a, machine of the Danner type plastic glass is drawn oi the end of a rotating tubular member referred to as a mandrel. 'I'his mandrel has an axial passage through which air is supplied to the unsupported end of the mandrel to produce a. bore in the glass being drawn therefrom. The tubing after passing from the mandrel moves downwa'rdlyi` and then travels in a horizontal path on a runway of rollers by which it is supported while on its way to the location where it becomes fully set and is seized by the drawing and severing mechanisms, as fully explained in the above Danner patents. As will be readily understood, since the end of the tubing remote from the mandrel is open to .the surrounding atmosphere a greater volume of air must always be supplied to the mandrel bore to maintain a desired cross-section of tube bore than would be necessary with the remote end of the tubing closed. This air to the tubing therefore is more wasteful of n air than in manual practice wherein all air introduced into the tubing remains therein until the drawing operation has been completed. Furthermore, in machine drawing of tubing, since the air supplied to the tubing rst passes through the highly heated mandrel any sublimate from the hot glass being drawn therefrom is swept forward into the cooler tubing and condenses thereon. 'Ihe impurities which are thus deposited on the inner surface of the tubing.

sometimes render the same unfit for some uses, for example in the manufacture of fluorescent lights. Also, it may be desirable to introduce gases into the trbingas it is being drawn, for example toimprove the internal surface of the tube. Thecharacteristics Iof such gases often preclude their being introduced intoI the plastic or hot end of the tubing.

One object of the present invention is an improved `tube drawing apparatus.

method of supplying -the chamber as l Another object is an apparatus for supplying a gaseous iiuid to tubing being drawn mechanically, closely simulating that followed in manual tube drawing practice.

A further object is a tube drawing apparatus wherein air or other gases may be introduced for use in practicing applicants method.

Fig. 1 of the accompanying drawing illustrates a Danner tube Ydrawing machine from which tubing is being ,drawn by a Danner drawing tractor and being cut into predetermined length tubes by a Danner cut-oi machine arranged within a sealed chamberv employed therewith in carrying out applicants method; and

Fig. 2 is a, view illustrating one manner of removing Sections of tubing from the sealed chamber.

Fig. 3 is an'enlarged elevational view in section of a fragment of the drawing machine appearing in Fig. 1.

Tube drawing is initiated in the conventional manner, for example, as taught by Danner by p air to the glass Ilthrough the initiallysupplying rotatable mandrel 9 of the machine I0 from a suitable supply line I2. The run of tubing II between the machine I0 and tractor I3 for drawing the tubing is supported on asystem of rollers (not shown) as is the usual practice.

In the structure illustrated, however, the tractorv I3 and cut-olf equipment I4 within a pressure chamber4 I5 into which the tubing enters through a suitably hushed Kopening I6. A gas supply line I1 extending from a suitable supply source (not shown) is in communication with chamber I5 and -contains a manually operable valve I8 and a magnetically operable valve I9. A\ manometer 20 in communication with the chamber I5 indicates the pressure within the chamber. This manometer also serves as a pressure control switch through which current is supplied from a source :v-y to the valve I9 to maintain the supply line closed so long as a predetermined pressure exists Within the manometer the valve to open only when a further supply of gas to the chamber I5 is required to maintain the desired pressure in this chamber.

As clearly brought out `inthe previously referred to Danner Patent 1,220,201, the tubing I I is severed into predetermined length tubes II by cut-oiequipment I4 and dropped into a trough of a delivery wheel 25. I In the structure an apparatus suitable are arranged the tubing suitably expanded.

' tice, chamber I5 can illustrated the tubes Il' roll from the delivery wheel 25 onto an inclined supporti where they are allowed to accumulate back of a gate 28 opening to a small chamber 30. Accumulations of tubes II' in chamber I5 are periodically permitted to roll into chamber 30 by raising of gate 28. The accumulation of tubes II is periodically permitted to roll from chamber 30 by raising a gate 3|. Owing to the small capacity of chamber c 30 compared to that of chamber I5, pressure in chamber 30 is reestablished after lowering gate 3| by leakage from chamber I5 without a harmful drop in pressure within chamber I5. l

It may sometimes occur that tubes II' require manual manipulation and with this in view tools 3i and 32 are provided enabling an attendant observing the tubes through suitable windows33,

34 and 35, to shift the tubes II into proper' alignment. v

The tube drawing operation is initiated in the conventional manner, air being supplied to the mandrel from supply line I2, through the associated control valve V. After the drawing operation is progressing satisfactorily, valve IS may be opened to build up a iiuid pressure in chamber I5, the valve V beingv gradually closed as the pressure of the fluid supplied to the chamber and thus to the delivery end of the tube becomes high enough to maintain the unset portion of As will be clearly evident, the pressure maintained in chamber I5 may be such that 'valve .V can remain closed under which circumstances a static gaseous condition will prevail in the tubing being drawn as is the case in manual practice. Alternatively, if desired, the valve V may be operated to connect the mandrel with atmosphere and fluid from the chamber I5 thus passed through the tubing and mandrel in the reverse direction to that followed in past practice.

The structure illustrated contemplates the -use of some form of gas other than air. 1f air is to be employed as in common tube drawing pracbe so enlarged that an attendant can remain in means of suitable valves control the atmospheric pressure therein as required for best operating perfomance.

I claim:

1. The combination with a tube drawing apparatus wherein tubing is continuously drawn from a gathering tool, f a chamber into-which the drawn tubing enters, and means for maintaining a positive uid pressure in said chamber and in the bore of the tubing entering it.

2. The combination with a tube drawing apparatusl wherein tubing. is continuously drawn from a gathering tool having a bore through which fluid may be supplied to the bore of the tubing being drawn at its end of formation, of means for severing sections'of tubing from the free end thereof, an enclosure in which the free end of -the tubing is confined, and means for maintaining a positive fluid pressure within said enclosure and hence in the bore of the tubing entering it.

3. The combination with a glass working apparatus wherein a rotatable member is supplied intermediate its ends with moltenglass and the chamber and by asvaeae wherein glass is drawn from one end of the member in the form of tubing, of means for severing sections of tubing from the free end thereof and of fluid pressure apparatus associated with the free end of thetubing for maintaining a static and positive iiuid pressure within the bore of the tubing while the severing operation is occurring.

4. The combination with an apparatus wherein plastic glass is caused to flow continuously towards one end of a gathering device having a bore through which iiuid may be supplied to form a bore in the drawn glass and wherein the glass ing tension to is drawn and cut into predetermined lengths by suitable traction and cut-ofi equipment, of an enclosure for the cut-olf equipment having an aperture through which the tubing enters such enclosure, means for sealing the space between the enclosure and tubingv passing therethrough,

and means for maintaining pressure within said enclosure.

5. In a glass drawing apparatus, means for maintaining a constant predetermined static fluid pressure in the tubing as it is being drawn, said means comprising a sealed chamber into which the tubing projects and facilities forl maintaining a predetermined fluid pressure within the chamber in accordance with that to be maintained in the bore of the tubing entering it and means within said chamber for severing the tubing entering it into sections.

6. The combination of a glass tube former, of a drawing apparatus arranged to apply a drawtubing produced by the former, mechanism associated with said drawing apparatus for cutting the drawn glass into predetermined lengths, a walled enclosure for said mechanism having an aperture through one wall thereof through which the tubing enters, a gasket arranged to prevent passage of fluid out of the enclosure around the tubing and means for maindrawing apparatus, a chamber tubing is delivered, means within said chamber for severing the tubing into tubes of predetermined lengths, means for maintaining positive pressure in said chamber, and means enabling the removal of such tubes from said chamber while maintaining a positive pressure therein.

8. A glass tube drawing apparatus which includes a chamber having associated means for maintaining a positive pressure therein and into which tubing is delivered and severed into tubes of predetermined length, a second chamberhaving positive pressure maintained therein by fluid supplied from said first chamber, a gate between release tubes within said first chamber into said second chamber, and a gate for releasing tubes from said second chamber.

9. A glassl working apparatus which includes a chamber having a wall aperture closed to atmosphere by tubing passing therethrough still connected with a supply body of glass from which it is being formed, means within said chamber for severing the tubing entering it into sections,

CHARLES H. GREENE. i 

